Vehicle speed control or cruise control systems are well known in the prior art. Typical systems and methods allow a vehicle operator to engage a cruise control device to set and maintain a constant vehicle speed and to subsequently resume a previously set vehicle speed after interruption. Mechanical, electromechanical, and electronic implementations have been developed for a wide variety of engine types. A number of control strategies utilize either PI or PID closed-loop control of the vehicle speed based upon throttle angle position.
An alternative control strategy utilizes desired engine torque as an output rather than throttle angle position. In these types of control strategies, real-time dynamic information, i.e., instantaneous torque at the wheels, is continually obtained and recalculated for use by a controller in commanding output torque at the wheels rather than a position of the throttle. A problem encountered with such a strategy, however, includes roughness and initial dynamic oscillations upon initial entry into the speed control mode as well as transitions between dynamic operating modes.